Or – "And now for something completely different..."

Introduction

Sometimes when I'm bored I find myself trawling through websites for unusual hi-fi, and as I'm a vinyl nut I love all the weird and wonderful arms and turntables out there. Every so often I find something that is so unusual I feel I have to chase it up and this was certainly the case when I saw the Abis SA-1.2 tonearm on Phillip Holmes 'Mockingbird Didtribution site', his USA site having some very interesting kit and his patience with my innumerable questions exemplary ;-)

You see my first reaction on seeing it was 'wow! A copy of the Dynavector 507!' ../sorgenti/dynavector507_e.html - the same finish (from pictures) the same machined 'girder' of an armtube*, the same bent offset structure and SME headshell – just a bit more simple...

But on closer inspection I realised that the 'look' belied a totally different design – I just had to chase...

So to the nitty gritty

Design and construction

The arm was delivered, well packaged in a simple cardboard box/foam insert. Nothing 'flashier' is needed and I rather like the punters money going on the contents rather than the box that holds it!

Inside I found a beautifully finished product very much in the mold of the big Dynavector (which costs multiples of the SA 1.2's price) with classic camera chrome and polished chrome finish. Picking it up it both looked and felt a quality item. There was obviously no play in the bearings and everything works with smooth precision – an engineers arm.

Which brings us to the very unusual appearance and the various design compromises** involved.

The first and most important decision the designer has made is to use an SME headshell fitting. I have discusses the consequences both good and bad of this in some length in my review of the Pro-Ject Signature 12 turntable so forgive me if I don't repeat it all here but in essence that one choice dictates much of the design of any tonearm using such a headshell. The bottom line is that such a headshell carries no offset so the offset angle has to be supplied by the armtube being bent into an S or J shape, or, as in the case of the Abis and Dynavector 507, by mounting a stub arm of some kind at an angle to the main armtube.

The result of this is that the armtube will be inevitably unbalanced – both statically and dynamically producing a skewed Ellipsoid of Inertia as the stylus is always well to one side of the main arm axis. This imbalance is obviously controlled by the bearings of the arm – and the design of the bearings appears far superior in this respect than on the Pro-Ject arm but in an ideal world it would be better to evenly load the bearings.

The SME mount obviously brings other compromises – the addition of at least 4 soldered and pressure joints per signal wire, a reduction in rigidity and of course a mechanical joint right by the headshell. These factors (plus cost considerations) have meant that the number of high-end arms sporting SME mounts has diminished to a mere handful.

But the choice, as with all good compromises, is balanced by two advantages – one obvious the other less so but if anything more important.

The obvious one is that cartridge swapping is an easy and relatively safe procedure. If the arm has a fairly easy VTF and anti-skate adjustment (and the Abis is pretty good) then swapping from one cartridge to another is the work of a moment and so inveterate cartridge swappers have an excellent and economic alternative to multi-arm turntables.

But the more fundamental advantage is that the use of such headshells gives simple and effective control of Effective Mass (EM) so that cartridges can be properly matched to the arm in a way that very few others allow.

The Effective Mass Problem...

I've discussed this at some length in my SME V12 review but here I think it's worth revisiting the subject as since the relative demise of the SME mount the control of EM has gone from most arm designs.

The reason that EM is important is simple because it acts with the compliance (bouncyness) of the cartridge cantilever to produce a resonance frequency. Conventionally this resonance frequency is set to be between about 7 and 16 Hz. The upper limit is straightforward – the audio spectrum and indeed some speakers output begins from this figure, so if say a 20 Hz signal was recorded and the resonance was 20 Hz the cartridge would vibrate more and more and more until it jumped out of the groove and made horrible noises in the meantime. Below the lower figure warps, footfalls and the suspension of some turntables mean that they too will cause the cartridge to bounce at resonance and either leap from the groove or skate across the record – cuing becomes nearly impossible.

Effective mass is not a measure of the inertia of an arm measured at the pivot (which rises significantly with an increase in arm length for example) – rather it is a measure of inertia as seen by the cartridge and so the influence of the masses in the arm falls exponentially as you move away from the cartridge itself. What that means is that 1 grm added to the cartridge weight adds one-whole-gram to the Effective Mass. Adding the same weight half-way down the tube will have a tiny effect, added right by the pivot the change of EM will be to all intents-and-purposes – zero.

With a fixed headshell, an arm will have a nominal EM (an SME V12 is 12 gr for example) and ALL of the rest of the EM will be supplied by the cartridge itself. So if a cartridge manufacturer has tuned the suspension to give a resonance of say 10 Hz when matched with an EM of 20 gr, they will have to make the cartridge body weigh 8 gr and assume that people will only use arms of around 12 gr EM.

Now all of you who have followed me up to now will see what's coming;-) If you have a removable headshell then suddenly you have total control over EM. Abis quote an EM of 20 gr with the supplied headshell which makes it pretty high mass. But the headshell is one of the heavier of the breed – let's say 12 gr – replace it with a lightweight Magnesium headshell of say 4 gr and you have an arm with an effective mass of 12 gr, placing the arm well into the medium EM range.

And a quick look on Ebay will find hundreds of different headshells with huge variations in mass and myriad constructions, wood, carbon fibre, plastic, Aluminium etc etc – a tweaker's delight;-) And with headshells running from a couple of Euro to many hundreds you can spend many a happy hour experimenting with EM and materials.

Is that worth the downsides of the choice? Only you can decide, but it's certainly a valid choice either way and the arrival of a new SME headshell equipped arm with high-end pretensions can only be welcomed.

Having got that out of the way let's look at the rest of this very unusual arm.

The common way of providing the cartridge offset needed on an SME headshell arm is, as I've mentioned to just bend a tube to the required angle and stick the mounting collar on the end. On the Abis 1.2 the main armtube is straight and machined from a solid billet of aluminium. At the end a second 'tube' is securely bolted to the main-tube using a machined block – the resultant construction being of 'battleship-build' and that substantial stub-arm located close to the cartridge is a contributor to the rather high EM. Just behind this joint is a hole into which can be placed an extra weight to raise the EM even further (another tweak for EM!).

Half way down the main armtube there is a machined slot carrying a sliding weight. This is marked out '0,1,2 and 3' and by balancing the arm with the weight at '0' and then sliding this weight forward you can adjust VTF very quickly – the weight being locked into position with a small knurled nut. The markings correspond very approximately with 1, 2 and 3 gr but as they vary depending on cartridge weight it's best to use them as a reference point to return to after having used proper scales. Of course this weight can equally be used as a fine adjuster for EM though by now I think we're probably getting too obsessive... Abis also claim that this structure will also have an effect on the resonance behavior of the arm itself by breaking up standing waves and that by moving and locking this in different positions we have another tuning device. Sounds possible I guess – I couldn't really hear anything.

Anti-skate is provided by another knurled adjuster acting via a very short thread to a spring and marked again '0,1,2, and 3'. At '0' the thread remains slack of course. Unfortunately at '1' the thread remains slack until well onto the record so that for the first 1/3 of the record there's no anti-skate and then it kicks in. At '2' the thread is under tension all the way but the whole thing isn't very convincing and to be honest a little too clever for its own good. A simple pulley and weight would be a neater solution.

The counterweight is a solid affair locked with an grubscrew and a small parasitic weight can be added at the end of the counterweight stub for heavier cartridges (and to further tune EM!) - with even moderately heavy cartridges this is necessary – personally I'd have specced a heavier main counterweight or perhaps a choice of two as many manufacturers offer so as to keep the counterweight tight to the bearing.

Arm height is altered with the classic grub-screw and wiggle but is very smooth – I tend to prefer such a simple approach...

What all this doesn't tell you is that the whole thing is beautifully put together, bearing quality was superb, the machining and finish exemplary – very nearly up with the Dynavector 507 – and attention to detail like the wiring running in tiny tubes very gratifying. It does all add up to an armtube full of bolts and joints and other pieces which rather bucks the modern trend, but the-proof-of-the-pudding-is-in-the-eating...

In Use and Sound Quality

The Abis was mounted on two turntables – the one used for most of the test was the Acoustic Solid but the arm also had a try-out on my home grown Langer Direct-Drive 'Plank'...

Setting-up was very straightforward using the supplied template and I fitted the Dynavector DV 20x2 which is a typical and very fine medium-compliance cartridge.

As supplied the resonance frequency of the combination turned out to be 6 Hz – below the ideal. It did make cuing a slightly more fraught process than usual but not to the extent that I was deterred from using them together. In fact I did get to wondering about that lower limit. In the days when almost all quality turntables were suspended such a limit was more important. I remember not being able to use a V15 on my SME/Gyro combination because of the difficulty of cuing and bounces at the slightest warp, but the foundation of the Acoustic Solid on a slab of Granite on a very solid base made it considerably less critical and I think you need to look at your own situation before deciding on this.

Swapping out the supplied headshell for a much lighter one bought from Ebay for 8 Euro gave a resonance of 9 Hz but to be honest – in my situation – I actually preferred the supplied headshell.

All this swapping about really did bring home the convenience of that SME mount, and took me back to my years with the Dynavector 507 which I remember with great affection. And in some ways the Abis reminded me a little of that world-class tonearm.

This is not an arm that is brilliant at everything. My recent experience with the SAT tonearm has really made me reassess (at massive cost) what is actually on a record. To compare the Abis with an arm 20x its cost isn't the purpose of the exercise but such a reference (sadly a memory only) does allow me to pick holes and more fair comparisons with arms such as the Audiomods brings up strengths and weaknesses of the design.

So here goes... The bass goes very deep and is pretty tuneful with bass-lines easy to follow. I'm a Stranglers fan and ol' Jean-Jaques has a lovely crunchy sound. The SA 1.2 happily provided the weight, tune and rhythm but did sound a bit 'soft' compared to the best – the sort of thing where you can tell thumb from plectrum, or old strings from new... Likewise where a kick-drum (or Gross Caise in 'An American In Paris') hits you in the gut the wave front is a little diminished.

The top end was a little shy, lacking some 'shimmer' and sparkle especially in some really well recorded jazz and but on occasions throwing up just a slight tizzyness – this is nit-picking as overall it was pretty good and not intrusive unless you are used to something better but a characteristic nevertheless. However playing with headshells might well swing this one-way-or-another.

But if the Abis is never going to satisfy those searching for the very finest detail of high-hat or 32 foot organ-pipe, where it really scores is in the most delightful midband – and after-all that's where the actual music is;-)

Here the slightly soft, charming character remained, I found myself relaxing in front of record after record where vocalists had room to breath, clarinetists swung and polyphony ruled. At one point I just dug out all my old Simon and Garfunkel records and wallowed in nostalgia. For all this sounds like a bit of retro mid-fi that's not my intention at all. Some of those recordings are world class and combinations like close harmony and acoustic guitar often fall apart as the delicate balance between them is broken as first one or the other dominates, a resonance blooms out or a few higher guitar notes rattle out of the mix. The Apis handled all this as well as anything I can remember.

When I'm 'testing' as opposed to 'listening' I often use street scenes like Madonna's in 'I love New York' where some systems really throw out a street ambiance into the room. The Abis did OK but not as well as the Audiomods, but kept everything in place and believable – the nice thing is that having 'tested' this you get the buzzy electronic synths of the song itself and the contrast was beautifully handled with all the edge and bounce you could wish for. I'd recommend this as a great song for anyone wanting to see how dynamic and well produced modern 'Pop' can be (only on vinyl – the CD is hopelessly compressed) and the SA 1.2 won't disappoint.

One of my other recent 'killers' is Nancy Griffith's Last of the True Believers' which needs utter control to stop her voice going from unique to fingers-down-a-blackboard – think Nora Jones at one end of the Spectrum and Ms Griffiths at the other - and thankfully I could sit through the whole album and listen with great pleasure

As hinted before soundstaging is good both in width and depth without being class leading, but the size and solidity of the performers were both stable and realistic which is, in my book, rather more important helped along by good reproduction of dynamic swings both of the 1812 and struck guitar string kind.

Conclusion

Overall I'd rate the sound as being a little off-the-pace in the extremes but excellent elsewhere and a real pleasure to listen to with a quality moving-coil. It's competitive with other arms from a purely sonic point of view if not the best of the bunch (The Audiomods gets that vote). What it does have is superb ease of use, a rare ability to go from a medium-mass to a true high-mass arm so it can match various cartridges in your collection including some of the more exotic or classic (SPU's spring to mind) low-compliance cartridges. No other arm I can think of, even others with SME headshell mounts, offers quite so much flexibility. As someone fond of cartridge swapping is quite likely to use disparate cartridge choices (otherwise what's the point) this flexibility is unique. It looks, and in fact sounds very like the Dynavector 507, but though the design of the arm belies the superficial similarity, the SA 1.2 joins the Dynavector in being one of the few arms that combine the flexibility and convenience of the SME mount with excellent sound quality.

Musings

Looking at the design one thing immediately struck me. Using much the same tooling it ought to be possible to make a straight – fixed-headshell arm of any length sticking to the same mount/bearing-housing/counterweight etc and at lower cost. Now I wonder how that would sound?

*Yes pedants – I know it's not a tube...

**Some manufacturers don't like my use of the word 'compromise' and ask me to try use another word if possible (in the nicest way of course). So I'll just clarify the situation and make a plea for the use of the English language and a retreat from 'ad-speak'. Let's make one thing 100% clear. Everything mankind has produced over the last 100,000 years, from the first pointed stick to a F1 car is a mass of compromises. When I see a manufacturer use the phrase 'a no-compromise design' I reach for my gun – it's meaningless drivel. To say a designer has made compromises is like saying something is made of atoms – is stating the blindingly obvious. My job as a reviewer is primarily to explore and describe the compromises a manufacturer has made and to explain, where I can, the effect these design choices have – both good and bad – End Of Message...